1. Field of the Invention
This invention relates to an image inspection method which inspects drawbacks such as flaws, the mixing of foreign matter, and cracks in, for example, a wafer or substrate of semiconductor, and an image inspection apparatus which employs the method.
2. Description of the Related Art
An image inspection method in the prior art has been such that illumination light is transmitted through or reflected from an object to-be-inspected by employing illumination with infrared radiation or the like, and that the object to-be-inspected is visually inspected on the basis of a resulting transmission image or reflection image.
An example wherein the object is inspected by transmitting the illumination light therethrough is disclosed in Non-patent Document 1, that is, Optical μ-Crack detection in combination with stability testing for in-line-inspection of wafers and cells, 20th European Photovoltaic Solar Energy Conference, 6-10 Jun. 2005, Barcelona Spain. and an example wherein the object is inspected by reflecting the illumination light therefrom is disclosed in Patent Document 1, that is, Japanese Patent No. 3,220,690
The image inspection method of the above mentioned prior-arts, however, is chiefly based on the visual inspection. Although automatic inspection is declared to be possible, means therefor is not stated, and the practicability thereof is very scanty.